Apparatus for drying loose fibrous materials



July 24, 1956 H. FLEISSNER 2,755,513

APPARATUS FOR DRYING LOOSE FIBROUS MATERIALS Filed Dec. 30, 1953 m m gvNWWAV \YNA 77 73 1V 7 APPARATUS FOR DRYING LOGSE FIBROUS' MATERIALS HansFleissner, Egelsbach Kreis Olfenbach (Main), Germany, assignor to FirmaFleissner & Sohn, Maschinenfabrik, Egelsbach Kreis Oifenbach (Main),Germany The present invention relates to an apparatus for drying loosefibrous materials.

The apparatus is of the type comprising a disintegrating unit and a pairof superposed perforated cylinders to which the disintegrated flakes areconveyed by means of a circulating current of air. The air current isgenerated by a fan and is made to pass a radiator on its Way to thecylinders; part of the air current is branched otf and made to travel tothe rear side of the upper perforated cylinder.

In machines of this known type, the disintegrated fibers or flakes aremade to adhere to thecircumference of the perforated cylinders, where aneven thick fleece is formed depending on the feeding of the air currentand the adjustment of guideplates covering part of the cylinders.

The known machines, however, have the inconvenience that the aircirculation has to be under constant surveyance by operating a number offlaps. When the-control and adjustment of these flaps are not carriedout at the proper time, disturbances are likely to come up in the fleeceformation and the machine can no longer be operated continuously. A verymarked disadvantage is, furthermore, the occurrence of a strong eddyformation at the rear of the upper perforated cylinder. This is likelyto interfere with the entire air circulationsystem. The eddies disturbfleece formation at the rear of the cylinder to such an extent that someplaces of the" cyliinder become completely uncovered. This, in turn,interferes with the vacuum in the upper cylinder so that the whole aircirculation is disturbed.

In addition to this drawback, there is a further inconvenienceinterfering with the air circulation. This is the fact that in the knownmachines the beaters, too, have a certain fan action whiledisintegrating the starting material into flakes. Cold air is therebyadmitted into the system which lowers the temperature of the hot airreaching the perforated cylinder. This in turn reduces the temperatureof the cylinder itself to an extent that water is condensed on thecylinder from the moist air. Such condensation is, of course, another inconveniece which counteracts the drying action of the machine.

The eddy formation at the upper cylinder is caused primarily by anunsatisfactory air circulation in the known machines. In these machines,the fan is enclosed completely in a spiral casing from which air iswithdrawn through an adjustable flap. This air removal causes a strongturbulence which, as stated above, is a serious drawback in theoperation of the machines of this type.

It is the object of the present invention to overcome the shortcomingsof the known machines and to provide an apparatus permitting acontinuous flawless formation.

It is a further object of the invention to provide means for continuousoperation without adjustment of the machinery during. said operation atthe time when new material is fed thereto.

Finally, it is an object of the invention to provide machinery in whichmaterials of varying moisture content can be driedunder even workingconditions.

Other objects and advantages of this invention will become apparent fromthe following, description and the acompanying drawings.

The machine according to the invention comprises a scroll housing whichcompletely encloses a fan for the generation of an air circulatingsystem. The casing contains two separated air ducts, one of which servesfor feeding air over a heater to the disintegrating unit, whereas theother duct conveys air to the rear side of the upper of two perforatedcylinders. By this air circulation through separate ducts, which isbrought about by the subdivision of the spiral easing into two parts,the air current at the rear of the perforated cylinder is calmed down tosuch an extent that no more disturbances in fleece formation will occur;the air circulation in the entire machine is very uniform and operationcan be made to function continuously, without interruption.

A further characteristic feature of the invention is the arrangement ofa completely closed system of the circulating air passing by thedisintegrating unit- In the known drying apparatus of the present type,a flap has to be provided as an outlet for the air drawn into the systemat another place. This is necessary because of the irregularity of theadmission of fresh air by the fan action of. the beater. Thebefore-mentioned arrangement causes considerable heat losses in thewhole system since the air is at high temperature at the withdrawal spotof the circulating system.

According to the invention, the disintegrating unit, which preferablycontains a spiked drum,v is included in the drying chamber and the aircirculating system is completely closed. It is thereby accomplishd thatthe heat in the air is retained in its entirety, since no fresh air isadmitted which could cool down the circulating air and'could lead tomoisture precipitation in the perforated cylinders.

The: use of a spiked drum conjointly employed with the air circulatingsystem according to the invention has the advantage that spikes have afar lower fan action and will therefore not suck in fresh air from theirenvironment into the circulating system.

It is a further advantage of the present invention that additionalheaters are provided inside and/ or outside of the perforated cylinders,so that the cylinders will be heated up to a degree that will insuretheir remaining dry at all times.

A machine built according to the invention operates continuously withoutcondensation of moisture occurring on the cylinder walls and withoutother disturbances. Furthermore, the drying efficiency of the machine isincreased due to the fact that a drying action is already performed inthe take-in-cylinders which is equal to about half the drying action ofone of the perforated driers.

An apparatus according to the present invention is shown more fully inthe accompanying drawing, in which corresponding parts are designated bythe same numerals in the various figures of the drawing.

Fig. l is a vertical longitudinal section through the center of mydevice provided with a drier of the straining drum type.

Fig. 2 is a vertical longitudinal section through the center of anotherembodiment of my invention in which a belt drier is used.

Fig. 3 is partly a sectional view along line III-III of Fig. l and showsone of the large driers in elevation; and

Fig. 4 is a section along line IV-IV of Fig. 2.

Referring more particularly to Fig. l, which shows a disintegrating unitwith the perforated take-in cylinders, an associated fan and the heatersfor the cylinders, as well as the large driers in cross-section, numeral1 desig nates a conveyor band onto which the fibrous goods to be driedare placed by hand or by any mechanical device. Before this happens,water is eliminated from the goods by a centrifuging or sqeeuzingprocess.

Arranged ahead of the conveyor 1 is a pair of takein rollers 2, whichare arranged in the neighborhood of the spikes of the disintegrator 3.The spikes are so close to rollers 2 that there is hardly any gap left.The spikes are driven past at high speed and tear the fiber materialemerging from the rollers into fine flakes, which are thrust bycentrifugal force through a channel 4 to take-in cylinders 5 and 6.

The cylinders 5 and 6 are open atboth ends and are connected to a fan 7which sucks out air from the interior of cylinders 5 and 6 through ducts8 and 9. Fan 7 is so constructed that it returns part of the air by theshortest route 12 to the upper cylinder, whereas the remaining part isconducted by Way of heaters 10 and a channel 11 to pass disintegrator 3and is carried through channel 4 to the front side of cylinders 5 and 6.Where the air passes the disintegrator 3, the channel 11 is very narrowand air velocity is great, whereby the flakes are withdrawn and carriedalong from the spikes of the disintegrator.

For that purpose, the fan casing is so constructed that two separate airducts 12 and 13 are provided therein. Duct 12 carries air at reducedpressure to the rear side of the upper cylinder, whereas duct 13 pressesair through heaters 10 and by way of channels 11 and 4 returns it to thefront side of the cylinders. The air movement is enhanced by the rapidrotation of the disintegrator 3.

In the interior of the cylinders S and 6, guide plates 14 and 15 arearranged, which prevent the aspiration of air through the covered partof the cylinder wall. These plates serve the purpose of preventing fiberflakes to adhere to those parts of the cylinder walls where theiradherence is not desired. In the free portions of the cylinders, flakeswill adhere at the front and fleece will form at the rear, whereafterthe fleece is caused to travel from one larger drier 20 to another one,while being under the suction of dry air.

The fleece formed in the take-in cylinders may also be placed onto oneor more conveyor bands 21 and carried through the drying chamber thereon(see Figs. 2 and 4). r

In Fig. 1, heaters for the upper cylinder 5 are shown at 16 and 17;heaters for the lower cylinder 6 are designated by 18, 19. These heatersmay be of any known design.

What I claim is:

1. A device for drying loose fibrous material, comprising afiber-disintegrating unit, a pair of perforated cylinders one arrangedabove the other, means for generating an air current capable oftransporting the particles disintegrated in said unit to said cylinders,means for heating said air current, and means for drying a fleece ofsaid fibers formed on said cylinders, said device being provided with ascroll housing; a fan arranged therein for generating said air current;two separated air ducts one of them discharging air over said heatingmeans to said disintegrating unit, the other one supplying air to therear of the upper one of said two cylinders.

2. A device for drying loose fibrous material according to claim 1,wherein the disintegrating unit consists of a spiked drum built intosaid drying chamber and completely enclosed therein.

3. A device for drying loose fibrous material according to claim 2,wherein the air system is a circulating, completely closed system.

4. A device for drying loose fibrous material according to claim 1including additional heating means inside the perforated cylinders.

5. A device for drying loose fibrous material according to claim 1including additional heating means outside the perforated cylinders.

6. A device for drying loose fibrous material according to claim 1including additional heating means both inside and outside theperforated cylinders.

References Cited in the file of this patent UNITED STATES PATENTS423,598 Duncan Mar. 18, 1890 663,868 Crean Dec. 18, 1900 868,063 AngusOct. 15, 1907 930,756 Howarth et al Aug. 10, 1909 1,377,793 Schwartz May10, 1921 1,774,309 Anderson Aug. 26, 1930

